A pigeon sparks a spy hunt. The clock is ticking and the bunker is calling.

In this final episode of our four part nuclear series, Matthew Syed examines the current nuclear landscape. In this complex, multiplayer context how do we create a safer world?

We begin in Kashmir, the disputed territory between India and Pakistan, where mutual suspicion has led to nuclear expansion and a delicate balance of power. With our sights understandably on the Ukraine crisis, Matthew argues that while our current nuclear ecosystem persists, there could be other flashpoints that we’re not paying enough attention to.

Matthew enters the worrying world of nuclear modelling and hears about research that suggests the threshold for catastrophic nuclear damage is lower than we might think. And we’re taken down into the bunker to understand why some people believe safety really lies in their own hands.

But is bunkering down the solution? And is planning for the worst actually a hopeful act - you are planning for there to be a world to re-join in the end?

As our series ends, Matthew asks whether we can reconcile different ideas about how to contain nuclear weapons, wake up and regain agency, to chart a path to a safer future.

Guest list: SJ Beard, Academic Programme Manager at the Cambridge Centre for Existential Risk Dr Annie Waqar, Academic Consultant, UK & South Asia and nuclear arms control researcher Bradley Garrett, author of Bunker: Building for the End Times and Assistant Professor of Geography at University College Dublin Professor Brian Toon, University of Colorado. Paul Ingram, Academic Programme Manager at the Cambridge Centre for Existential Risk Beatrice Fihn, Executive Director of the International Campaign to Abolish Nuclear Weapons Sir Lawrence Freedman, Emeritus professor of War Studies at King’s College London and nuclear strategy expert.

Presenter: Matthew Syed Producer: Pippa Smith Researcher: Nadia Mehdi Series editor: Katherine Godfrey Sound design and mix: Rob Speight Theme tune by Ioana Selaru A Novel production for BBC Radio 4.